fix: change example comment to match type

[eschutho]

I updated the type for this config but forgot to update the comment.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #21772 (812e4b8) into master (bd3166b) will decrease coverage by 11.54%.
The diff coverage is n/a.

❗ Current head 812e4b8 differs from pull request most recent head f3301e6. Consider uploading reports for the commit f3301e6 to get more accurate results

@@             Coverage Diff             @@
##           master   #21772       +/-   ##
===========================================
- Coverage   66.88%   55.33%   -11.55%     
===========================================
  Files        1802     1802               
  Lines       68987    68987               
  Branches     7345     7345               
===========================================
- Hits        46139    38173     -7966     
- Misses      20951    28917     +7966     
  Partials     1897     1897               

Flag	Coverage Δ
hive	?
mysql	?
postgres	?
presto	52.83% <ø> (ø)
python	57.58% <ø> (-23.89%)	⬇️
sqlite	?
unit	51.05% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/config.py	90.99% <ø> (-0.65%)	⬇️
superset/utils/dashboard_import_export.py	0.00% <0.00%> (-100.00%)	⬇️
superset/tags/core.py	4.54% <0.00%> (-95.46%)	⬇️
superset/key_value/commands/update.py	0.00% <0.00%> (-90.91%)	⬇️
superset/key_value/commands/delete.py	0.00% <0.00%> (-87.88%)	⬇️
superset/db_engines/hive.py	0.00% <0.00%> (-85.19%)	⬇️
superset/key_value/commands/delete_expired.py	0.00% <0.00%> (-84.00%)	⬇️
superset/dashboards/commands/importers/v0.py	15.62% <0.00%> (-76.25%)	⬇️
superset/datasets/commands/update.py	25.00% <0.00%> (-69.05%)	⬇️
superset/datasets/commands/importers/v0.py	24.03% <0.00%> (-69.00%)	⬇️
... and 285 more

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[Antonio-RiveroMartnez]

LGTM!